'48 Fuel pump one way valve

[Bruce Fenstermacher]

Did a little computer sleuthing today on the subject of the Parker #475-GG-1/4D one way valve required of the'48 fuel system.

We have several threads on the subject of this valve and the full pump requirement of the '48 and I wanted to tie them together and record what I found today.

Here are the other threads:
http://cessna170.org/forums/viewtopic.p ... adcd8d3aba
http://cessna170.org/forums/viewtopic.p ... opper+fuel
http://cessna170.com/forums/viewtopic.p ... 31dfb5f4cd

In the last thread listed above George stated that Parker #475-GG-1/4D was superseded to PN:453/1/4/26. I could not find anything with that number but after a few searches with slightly different syntax I hit on this: Teledyne 453-1/2S2-6. BINGO we have the syntax. I quickly substituted 1/4 for the 1/2 and low and behold we have lots of hits. Seems you can find it under Parker or Teledyne and Parker Teledyne. Search for 453-1/4S2-6

https://www.mscdirect.com/product/details/80255383
Specs
Type Check Valve
Material Steel
Maximum Working Pressure (psi) 5000.00
Inlet Size 1/4
CV Rating 1.600
Thread Type NPT
MSC Part #: 80255383
Mfr Part #: 453-1/4S2-6
453- 1/4 S2-6

Another description states the valve uses buna-n seals. Its length is 2.69" and .81" diameter.

I've seen then listed as cheap at $19 surplus to nearly $500 but the going price seems to be just under $256 at MSC.

I don't know if this will work or where George got his info that the original was superseded to this number. But is sure looks promising.

[GAHorn]

The OEM valves I've seen look nothing like that and have male threaded end-fittings...making me wonder if this is actually the part in which we are interested.

[n2582d]

Bruce, your sleuthing is amazing! Right up there with Gene and the 60 amp. ammeter. I'm very impressed! One difference between the part you've shown and the original may be the material. I'm guessing that the original was aluminum as indicated by the "D" after the 1/4. In contrast, your example is made of steel and has an "S" after the 1/4. Doing a search I found another part number which supersedes the original. Part number 0550100-10. KRN has one.

Now regarding whether this check valve has male or female threads. The IPC shows two variations for how this valve is plumbed; in the top right corner on Fig. 34 is the early version, (s/n 18001-18220) as shown here.

Check Valve.jpg (45.9 KiB) Viewed 30529 times

At the inlet to the check valve is an unlabeled tee. Clearly though it has a male pipe fitting which screws into the check valve. This would appear to be an AN825-6D.

AN825-6D

AN825C.jpg (109.06 KiB) Viewed 30529 times

At the outlet of the check valve is a AN911-2 nipple.

AN911-2

AN911C.jpg (1.94 KiB) Viewed 30529 times

The bottom right corner of Fig 34 illustrates the later setup, (s/n 18221-18729):

Later Style.jpg (47.11 KiB) Viewed 30529 times

Notice that the AN826-6D tee has the male pipe on the run which screws into the check valve.

AN826-6D

On the downstream side of the check valve there is no nipple. The male pipe thread of the cross screws right into the check valve.

[GAHorn]

Well, I may have gotten caught by the same Grinch that I've warned others of...
Just because you've found it on your airplane doesn't mean it's actually OEM.
I've had two members send me their failed valves (looking for replacements) and both were male, almost identical to the Andair unit sold by Spruce for experimentals.
Checked with Cessna, and no help for those Members was forthcoming despite the earlier promises.
Excellent detective work indeed! Now to determine if it's suitable for fuels.

<edited corrections for auto-spell errors>

[Bruce Fenstermacher]

MSC is selling them under hydraulic valves. As I said, another source description stated it contained buna-N seals. BTW Parker or Teledyne is not the only manufacture I found such a valve manufactured. It might be that Parker has several manufacturers making these for Parker.

We will have to track down one of these valves on a 170 next week at Cody and look close at it and measure it to see how closely this valve is to an original.

[n2582d]

Off topic but maybe something one of you '48 170 owners can answer. Are all those fuel lines, fittings, and valve just supported at the carb inlet? Seems like a lot of weight and--being solid fuel lines--vibration to place on one fitting. Also, were those fuel lines to and from the pump and to the fuel pressure gauge originally copper or aluminum? Just curious.

[showe]

For what it’s worth here’s some pictures from N4039V. Believed to be original but couldn’t swear to it.

Gary the smaller primer line and fuel pressure line clamp I believe to a tab on the engine mount. If it shows up in the picture you’ll see the clamp that screws to it. Same thing on the larger lines to the pump. There are tabs that support it.

[n2582d]

Shawn,
Thanks for those pictures. Based on another picture I received by PM you do have the original check valve. The appearance and stamped p/n 475-GG-6 are identical. Was the spring removed from your check valve?

Your plane looks remarkably original. Still has the Goodyear wheels/brakes and old style throttle ball joint. Even the loops in the copper lines look similar to the IPC. Based on the serial number of your plane you should have the cross shown in fig. 34-36 "6-4-2-4 Krost Cross (Parker) ..." The IPC appears to show male fittings, NPT and AN. Is that what you have?

[Bruce Fenstermacher]

So Shawn, break out a ruler and give us the measurements of that original valve. How close is the supposed replacement I pictured, 2.69" in length and .81" diameter.

BTW I was amazed at the number of one way check valves of this type Cessna uses. Do a Google search for "Cessna check valve".

[showe]

Bruce, I’ll check that after work.

Gary, I assume this is the cross piece.

The fitting with filter was seized in the carb. Back to the check valve - the spring, ball and most of the seat were gone. Plane sat for at least 30 years so anything that the fuel could rust or corrode, it did.

[Poncho73]

I have an original check valve off my 48. I will take some pics tomorrow

[n2582d]

Shawn,
The picture of your cross answers the questions I had about it. Thanks again for posting that. That is one unusual fitting. Good luck to anyone trying to find that NOS! If you look at the text for these fittings in figure 34 most specify if they are either for pre s/n 18221 or post 18220. (See fig. 34-33 through 34-43). The items in common to both are the check valve and the fuel pressure line elbow, item 34-39, p/n AN822-2D. (The tee, 34-32, p/n AN826-6D, also appears to be common to both but, as previously explained, Cessna screwed up here. AN826-6D is for the later models and an AN825-6D should have been shown for the earlier models). The fuel pressure elbow Shawn has pictured is not an ordinary AN822-2D because it has a restricted orifice like the oil pressure line has (or should have). My guess is that Shawn's elbow is original. Frankly, that copper fuel pressure line, restrictor or no restrictor, makes me a bit queasy. If the line breaks with no restrictor there is a stream of pressurized fuel in the vicinity of the red hot exhaust pipes. With a restrictor it's probably a fine mist of pressurized fuel. Too vivid of an imagination I guess. I have never heard of NTSB reports where this has been an issue. But I have had 1/8" fuel primer lines break. See pages 2 and 3 of this discussion on restricted orifice elbows for oil pressure lines.

[n2582d]

... Back to the check valve - the spring, ball and most of the seat were gone. Plane sat for at least 30 years so anything that the fuel could rust or corrode, it did.

Here's a picture of the valve opened up. I assumed there would be a ball in there too but apparently there isn't one.

Quite remarkable that your valve still had the paper label on it. Can you read any of it? Bottom line might be "Pacific" Is that the top text in red too or do you think that is "Parker"?

[n3833v]

This is how my valve has been ever since I know. I will see if I can find my extra valve I bought years ago and bring it to the convention.
Had to edit the Fuel Pressure gauge line. I have the valve for reference. Thanks Gary for my lack of attention.

[n2582d]

We’re getting some good documentation of what the ‘48 Fuel plumbing looks like. Thanks for taking the time to photograph and label that John. Clearly the IPC left out a few details that these pictures fill in. John, are you sure that 1/8” line goes to the primer and not the fuel pressure gauge?

As uneasy as I am with pressurized 1/8” copper fuel line in the engine compartment it does have several things going for it vs. using hose. First it looks great; nothing says “Vintage” like some shiny copper tubing snaking around. Second, with a melting point of around 2000°F it’s way more fireproof than ordinary hose. Third, it’s FAA-approved, OEM, PMAed, TSOed, and blessed by the Pope - OK maybe not all of those, but some. I’ve found -2 stainless braided PTFE (Teflon) hose and -2 fittings online but they are not FAA-approved. Finally, it’s affordable, especially in comparison to custom-made hose.

For y’all with ‘48s does your IA check the function of that check valve during an annual inspection? Having fuel pressure on your gauge would indicate that the valve is closed, but short of removing the valve, or capping off the fuel pump outlet line and running the engine, how could you tell if it opens? Based on Shawn’s check valve, removing it to check that it is still working might be worth doing at annual.